Algebra I Math Problem

A gardener mixes x fluid ounces of a 20% liquid fertilizer and 80% water solution with y fluid ounces of a 5% liquid fertilizer and 95% water solution to make 30 fluid ounces of a 10% liquid fertilizer and 90% water solution.
a) Write a system of 2 equations with 2 variables to represent the situation.
b) What is the value of x?

Thanks in advance!

Proportion of fertilizer:

20x + 5y = (30)(10) = 300

Proportion of water:

80x + 95y = (30)(90) = 2700


To find value of x, first get an expression for y from the first equation:

20x + 5y = 300
5y = 300 - 20x
y = 60 - 4x

Now put that expression into the second equation:

80x + 95(60-4x) = 2700
80x + (95)(60) - (95)(4)x = 2700
5700 - 300x = 2700
300x = 3000
x = 10 fluid ounces.

We can also find y now, using:
y = 60 - 4x
y = 60 - 40 = 20 fluid ounces

Check:

20(10) + 5(20) = 200 + 100 = 300 as required
80(10) + 95(20) = 800 + 1900 = 2700 as required